Surgical procedures to alter the appearance of the human female breast comprise a substantial portion of the surgery performed by plastic surgeons. It has been estimated that 16 percent of the income derived by plastic surgeons in the United States results from such surgery. The surgical procedures frequently involve implantation of silicone based prostheses. Silicone implant mammoplasty is indicated in a variety of conditions, including cosmetic augmentation in micromastia, reconstructive augmentation in mammary asymmetry, and total reconstruction after mastectomy. The most commonly used breast implants are constructed of silicone gel contained within a silicone elastomer envelope. Less commonly used implants are constructed of a silicone elastomer envelope to which saline can be added to give the desired size or of a medical grade silicone gel-filled implant within a larger silicone elastomer envelope to which saline can be added. The first such implant of each type was developed approximately 20 years ago by the present applicant working in conjunction with another physician and with persons at Dow Corning Corporation. In the years since development, approximately one million pairs of these prostheses have been implanted; and, currently, they are being implanted at a rate of approximately one hundred thousand pairs per year.
Prior to development of the silicone elastomer enveloped, silicone gel prostheses, various agents were instilled directly into breasts to alter their appearance. Among the agents used were paraffin, processed petroleum, and silicone fluid. Usage of these directly instilled agents now is disfavored and largely has been discontinued because their use frequently was associated with local, often intense, inflammatory reactions. Additionally, migration of these instilled agents, particularly silicone fluid, has been associated with more generalized, potentially fatal tissue responses which vary depending upon into which tissue or structure the agent migrated. Human Adjuvant Disease may be a systemic effect of paraffin or silicone fluid instillation and is apparently an autoimmune connective tissue disorder that manifests as mixed connective tissue disease, rheumatoid arthritis, systemic scleroderma, or systemic lupus erythematosus. Onset of Adjuvant Disease has been reported as early as 2 years and as many as 25 years following instillation of breast augmentation agents such as paraffin or silicone fluid. In some cases, remission of the disease has followed removal of the augmentation agents; and in two cases, the disease has proved fatal.
Until recently, Adjuvant Disease had not been associated with implantation of silicone elastomer enveloped, silicone gel prostheses. However, within the last two years, there have been several reported cases where Adjuvant Disease followed implantation of these prostheses. In the only reported patient who developed Adjuvant Disease following prosthetic implantation where the prosthesis had been removed and examined, the silicone elastomer envelope was found to be ruptured; and free silicon gel was found free in the human cavity for the implant. Baldwin, C. M., and Kaplan, E. N., Silicone-Induced Human Adjuvant Disease, 10 Annals of Plastic Surgery 270 (1983). It also is known now that the silicone gel contained in these prostheses is composed of 96 to 98 percent extractable polydimethylsiloxanes (silicone fluid). Thus, the finding of Adjuvant Disease in a patient carrying a ruptured prosthesis combined with data establishing possible association of this disease with instillation of free silicone fluid indicates that the risk of developing Adjuvant Disease may be enhanced by rupture of silicone elastomer enveloped, silicone gel implants. Evidence suggests that patients predisposed to developing Adjuvant Disease are more susceptible to the disease following exposure to a foreign antigen.
Additionally, escape of the silicone gel from the envelope of the prosthesis is associated with other adverse consequences including satelliting of the gel into various parts of the soft tissue around the prosthetic pocket or down into the arm. Silicone gel in the soft tissue forms dense capsules and causes pain necessitating surgical excision of the gel. Recent data also suggest that the risk of infection in the tissue surrounding the prosthesis is increased following its rupture; and free silicone gel in the prosthetic pocket together with an infection may enhance synergistically the host tissue reactions to the implant. Therefore, ruptured prostheses should be removed as soon as possible; and if there is any evidence of infection or movement of the silicone gel away from the prosthetic cavity, ruptured prostheses should be removed immediately.
There are a number of causes of rupture of silicone elastomer enveloped, silicone gel prostheses. The prostheses can be punctured or torn accidentally during implantation procedures. If, after implantation, fluid which must be removed accumulates in the prosthetic pocket, a needle inserted to aspirate the fluid may pierce the silicone elastomer envelope. In 10 to 30 percent of patients receiving a prosthetic implant, a tight periprosthetic capsule forms which must be released. A closed capsulotomy, during which the breast is compressed forcefully by the surgeon's hands, is a procedure used to break the capsule and soften the feel of the breast. In approximately 30 percent of patients, a closed capsulotomy causes rupture of the prosthetic silicone elastomer envelope. Additionally, rupture of the silicone elastomer envelope can result from biodegradation of the envelope by tissue enzymes. Because of the relatively poor tear resistance of the silicone elastomer envelope, once a rupture or tear has occurred, it will propagate upon only minimal manipulation of the breast, freeing the silicone gel to escape into the prosthetic cavity and beyond.
Fold-fault failure also has been shown to be a cause of rupture of silicone elastomer envelopes, especially in prostheses containing saline. After implantation into the prosthetic cavity, the prosthetic envelope can become folded persistently along a particular line. By abrasion against itself along the fold line, the envelope progressively will wear away causing it to rupture along the fold line. Fold-fault failure of saline containing prostheses creates an emergency because the saline which leaks from the ruptured envelope is absorbed into the surrounding tissues. Absorption of the saline causes the prosthetic cavity to shrink. Thus, to avoid the need for a complete reoperation, rather than mere replacement of the prosthesis, the ruptured prosthesis must be removed immediately after rupture and replaced.
Although silicone elastomer enveloped silicone gel breast prostheses have been used extensively for 20 years and despite a demonstrated need to determine if silicone gel has escaped its envelop,, no prosthesis or non-invasive method has been developed which enables determination of whether implanted prostheses have ruptured prior to the onset of complication-related signs and symptoms. Also, no method has been developed to predict an impending fold-fault failure. In most cases, surgeons are unable to determine by external physical examination whether a prosthesis remains intact. Roentgenographic examination also has proved incapable of discerning the status of prosthetic envelopes because the X-ray density of the prosthetic envelope and its contents are not sufficiently different from the surrounding soft tissue to indicate whether there has been a rupture of the envelope or an impending fold-fault failure, and thus an escape or an impending escape of the contents into the cavity thus freeing the contents to migrate into surrounding or distant soft tissues.
This long-felt need for a prosthesis and a procedure which enables determination of whether implanted silicone elastomer enveloped, silicone gel implants remain intact now has been satisfied. Implantation of a prosthesis composed of a silicone elastomer envelope marked on the exterior of the envelope with a material, such as a radioopaque material, which absorbs electromagnetic energy to an extent different from the envelope, its contents, and the tissue surrounding it and enables production of an image of the marked envelope by irradiating the tissue bearing the marked implant with electromagnetic energy. An image showing that the pattern or configuration of the radioactive or radioopaque marker indicates that the envelope is intact. An image showing a change in the pattern or configuration of the radioopaque marker indicates that the envelope has ruptured or has a fold-fault which could develop into a rupture.
The material that absorbs electromagnetic energy to an extent different from the silicone elastomer envelope, the prosthesis contents, and the human soft tissue used to mark the silicone elastomer envelope can be incorporated within the envelope during manufacture or can be applied to the envelope following manufacture of the prosthesis. Marking the silicone elastomer envelope with one of several readily available radioopaque materials and producing an image by X-irradiation of the breast, as is done in mammography, has proved a successful application of this invention. The present innovation also is applicable to determining the status of other types of silicone elastomer enveloped, silicone gel prostheses and other types of silicone elastomer prostheses. Such other types of prostheses include various facial implants, penile implants, testicular implants, and carpal, metacarpal, and interphalangeal joint replacements and similar joint replacements used in the feet.
Further, marking the silicone elastomer envelope of saline containing prostheses provides a method for predicting fold-fault failure. To predict an impending failure, two or more serial electromagnetic energy produced images, such as mammograms, are compared. If the same fold line persists, the probability that rupture along that fold line will occur is enhanced. Also, a mammogram obtained while the breast was compressed along its lateral and medial aspects can be compared to one obtained absent breast compression. If a change in the initial pattern or configuration of the marker appears in the compressed and noncompressed mammograms, the probability of a rupture or that the identified fold line is persistent and will be a point of rupture is increased. Once a persistent fold line is detected, the surgeon can employ external manipulation or other techniques to alleviate the persistent fold, thus preventing rupture of the prosthetic envelope, or if necessary, remove the prosthesis and implant another one.